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authorLinus Torvalds <torvalds@linux-foundation.org>2017-02-22 17:33:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-22 17:33:34 -0800
commit7d91de74436a69c2b78a7a72f1e7f97f8b4396fa (patch)
treea43e68ae4ebbf0ec98678876d584fb0eb0303274 /init
parent6ef192f2259e78e1870c509fbd3040e6752b3b9c (diff)
parentd9c23523ed98a3acaa0bfd8fef143595d6aa631d (diff)
downloadlinux-7d91de74436a69c2b78a7a72f1e7f97f8b4396fa.tar.gz
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
Pull printk updates from Petr Mladek: - Add Petr Mladek, Sergey Senozhatsky as printk maintainers, and Steven Rostedt as the printk reviewer. This idea came up after the discussion about printk issues at Kernel Summit. It was formulated and discussed at lkml[1]. - Extend a lock-less NMI per-cpu buffers idea to handle recursive printk() calls by Sergey Senozhatsky[2]. It is the first step in sanitizing printk as discussed at Kernel Summit. The change allows to see messages that would normally get ignored or would cause a deadlock. Also it allows to enable lockdep in printk(). This already paid off. The testing in linux-next helped to discover two old problems that were hidden before[3][4]. - Remove unused parameter by Sergey Senozhatsky. Clean up after a past change. [1] http://lkml.kernel.org/r/1481798878-31898-1-git-send-email-pmladek@suse.com [2] http://lkml.kernel.org/r/20161227141611.940-1-sergey.senozhatsky@gmail.com [3] http://lkml.kernel.org/r/20170215044332.30449-1-sergey.senozhatsky@gmail.com [4] http://lkml.kernel.org/r/20170217015932.11898-1-sergey.senozhatsky@gmail.com * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: printk: drop call_console_drivers() unused param printk: convert the rest to printk-safe printk: remove zap_locks() function printk: use printk_safe buffers in printk printk: report lost messages in printk safe/nmi contexts printk: always use deferred printk when flush printk_safe lines printk: introduce per-cpu safe_print seq buffer printk: rename nmi.c and exported api printk: use vprintk_func in vprintk() MAINTAINERS: Add printk maintainers
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig16
-rw-r--r--init/main.c2
2 files changed, 10 insertions, 8 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 55bb6fb..483ad67 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -861,17 +861,19 @@ config LOG_CPU_MAX_BUF_SHIFT
13 => 8 KB for each CPU
12 => 4 KB for each CPU
-config NMI_LOG_BUF_SHIFT
- int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
+config PRINTK_SAFE_LOG_BUF_SHIFT
+ int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
range 10 21
default 13
- depends on PRINTK_NMI
+ depends on PRINTK
help
- Select the size of a per-CPU buffer where NMI messages are temporary
- stored. They are copied to the main log buffer in a safe context
- to avoid a deadlock. The value defines the size as a power of 2.
+ Select the size of an alternate printk per-CPU buffer where messages
+ printed from usafe contexts are temporary stored. One example would
+ be NMI messages, another one - printk recursion. The messages are
+ copied to the main log buffer in a safe context to avoid a deadlock.
+ The value defines the size as a power of 2.
- NMI messages are rare and limited. The largest one is when
+ Those messages are rare and limited. The largest one is when
a backtrace is printed. It usually fits into 4KB. Select
8KB if you want to be on the safe side.
diff --git a/init/main.c b/init/main.c
index c8a00f0..24ea487 100644
--- a/init/main.c
+++ b/init/main.c
@@ -581,7 +581,7 @@ asmlinkage __visible void __init start_kernel(void)
timekeeping_init();
time_init();
sched_clock_postinit();
- printk_nmi_init();
+ printk_safe_init();
perf_event_init();
profile_init();
call_function_init();